Phase-encoded optical sampling for analog-to-digital converters

A high-speed optical sampling system for electrical signals has been develo ped using a gain-switched diode laser and a dual-output Mach-Zehnder interf erometer, The optical phase shift between the branches of the interferomete r is highly linear in the applied electrical signal. The phase shift is enc oded in the two outputs of the interferometer and is recovered through digi tal signal processing. Analog-to-digital (A/D) conversion with 78-dB spur-f ree dynamic range is demonstrated. Our phase-encoded sampling technique all ows high-resolution (12-bit) conversion with high linearity at practical la ser power levels.